The invention refers to an apparatus and process for extracting metals from foundry sands and, more specifically, to an apparatus and process for extracting these metals by making use of a thermostated column.
In the field of metal extraction based on foundry sands, the extraction techniques most utilized to date in a liquid-solid system involve mechanically-stirred leaching tanks, the Pachuca tank and Bonotto, Kennedy or Rotocel extractors. None of this equipment, however, has been specifically designed to extract small quantities of metals from foundry sands, which represents a problem not, until now, resolved.
Of the conventional apparatus mentioned above, the Pachuca tank is that which most resembles the apparatus object of the present application. However, the thermostated column of the new apparatus differs from the Pachuca tank insofar as regards its air dispersion system, the use of decarbonated and humidified air, because it consists of a heating jacket and because temperature control of the heating fluid is by means of a thermostat. These features of an apparatus which it is desired to protect allow for a suitable pulp suspension, prevent the formation of a silicate and carbonate layer at the bottom of the column, permit better temperature control and a fine control of process variables, such as the pH, the air flow and the solution's oxidation-reduction potential.